The effect of nimodipine, a selective calcium channel blocker, on brain metabolism was studied during ischemia and recirculation in the gerbil. Nimodipine delayed the fall in ATP during the first minute of ischemia. This effect was significant in striatum and cortex, but not in hippocampus. Glucose levels after 5 min recirculation were significantly higher in striatum and cortex of nimodipine pretreated animals. These observations constitute the first demonstration of an effect of this class of drugs on brain metabolism. Nimodipine levels in brain were measured using a radioreceptor assay in which each brain homogenate provided the source of both binding site and competing ligand.